Despawned Mobs

I logged on and all my cows, 3 tamed horses, 3 tamed dogs, all my striders, a couple cats, and half my villagers had disappeared. That was on version 1.17.30 I assumed it was a glitch so I closed the game and opened it again same issue. I searched the forums and realized it had been happening to others and that there was a bug fix update so I downloaded the new update. Opened up my world and my mobs were still gone I’m devastated. I worked so hard to collect all those mobs just to have my progress erased…